1. Field of the Invention
The present invention relates to an undetachable flange joint adapted to be used as a clamping device for a supercharger to be mounted on an internal combustion engine and a method of manufacturing said flange joint.
2. Description of the Prior Art
A hitherto known typical clamping device for firmly holding a housing or casing of a supercharger is illustrated in FIG. 1. The components constituting the above clamping device are manufactured in the following manner.
The first step is to allow a strip of stainless steel sheet to be subjected to press forming until a semicircular configuration with a V-shaped cross-section as illustrated in FIG. 2 is obtained. After completion of a trimming operation a retainer 1 as illustrated in the drawings is formed, wherein it is cut to a predetermined circumferential length. Another strip of stainless steel sheet is subjected to press forming operation for punching a hole through which a trunion body 3 or a T-bolt is inserted. The blanked stainless steel sheet is bent to a loop configuration so that a strap 2a or 2b is formed. On the other hand, the trunion body 3 and the trunion cap 4 are prepared by way of the steps of press forming a strip of stainless steel sheet and then subjecting the thus obtained blank to drawing. The trunion body 3 and the trunion cap 4 are press fitted into the straps 2a and 2b.
Next, the head part of the T-bolt 5 is incorporated into the loop portion of the strap 2a in such a manner that it moves freely therein and both the layers of the strap 2a are spot welded to one another. Further, the trunion body 3 is also incorporated into the loop portion of the strap 2b and both the layers of the latter are spot welded to one another. Finally, the strap 2a with the T-bolt 5 included as well as the strap 2b with the trunion body 3 included are bent to the configuration corresponding to the outer diameter of the retainer 1.
After the respective components are prepared in the above-described manner, they are assembled one after another as follows.
The retainer 1 is mounted on a jig which serves to define the outer diameter of the retainer 1 and both the straps 2a and 2b with the T-bolt 5 and the trunion body 3 included therein respectively are attached to both the end parts of the retainer 1 with the use of a suitable jig which is not shown in the drawing. They are then spot welded to the retainer 1 at several positions. Next, the retainer 1 is removed from the jig and the T-bolt 5 is inserted through the trunion body 3. A nut 6 is screwed on the T-bolt 5. Now the preparative steps prior to be mounted on flanges are completed. It should be noted that FIG. 3 is a cross-sectional view of the finished retainer 1, taken in line B--B in FIG. 1.
The conventional flange joint is typically constructed by a combination of components in accordance with the method as described above, but the following drawbacks have been noted with it.
(1) The components have an intricate configuration and the flange joint itself is constructed by a relatively large number of components, resulting in increased man-hours and expensive manufacturing cost. PA0 (2) It is difficult to select the optimum spot welding conditions. Welding operation is required to be carefully conducted under proper control. PA0 (3) There is necessity for preparing special jigs for spot welding operations. PA0 (4) When the flange joint has a reduced inner diameter (for instance, less than 100 mm), roll forming is carried out with much difficulties. PA0 (5) Quick mounting and tightening are impossible, because it takes long time to open the flange joint to mount it on flanges of a supercharger. PA0 (1) The flange joint is constructed by a combination of only two kinds of components which are simple in structure. Thus, a press forming die for manufacturing them is easy to be prepared and press operation is carried out without any particular difficulty. PA0 (2) All the manufacturing steps starting from the press forming of the components to the mounting on flanges of a supercharger are conducted with the use of a press or the like machine. This causes mass-production to be practiced easily. PA0 (3) The flange joint can be manufactured at an inexpensive cost even when it has a smaller diameter (less than 100 mm) whereby it satisfactorily meet the requirement for a small size and light weight structure of the supercharger. PA0 (4) Any special step such as spot welding or the like is not required any longer and thereby the number of manufacturing steps is substantially reduced. As a result manufacturing is practiced at an inexpensive cost. PA0 (5) All the components are manufactured by way of press forming, resulting in their stable quality ensured.